A controlled environment unit has been compared with plaster dressings in the management of the below knee stump in 60 patients undergoing amputation for advanced vascular disease. The main criteria were stump healing and the speed of rehabilitation. There were 30 patients in each group. Three patients died within 10 days of operation. Primary healing was obtained in 65 per cent, secondary healing in 22 per cent and revision to above knee was required in 13 per cent. There were no statistically significant differences between the two groups. Neither did they differ in the times taken to reach the various stages of rehabilitation from bed exercises to independent walking with final prosthesis. While the controlled environment unit was as effective as the plaster dressing it tended to impede the patients' early mobility and to hinder nursing care. In particular it is not recommended for patients who may be confused or restless in the early postoperative period.